Apparatus and method of injection molding

ABSTRACT

An injection molded article with which a sheet-like material, such as a decorative sheet, is integrated is manufactured without causing damage to the sheet-like material. A molten resin injected into a mold cavity, passes smoothly a peripheral edge of the mold cavity, and flows into a groove portion without accumulating in the vicinity of the peripheral edge. When cooling the molten resin, the temperature of the molten resin in the groove decreases more quickly than the temperature of the molten resin in the mold cavity, because the volume of the groove portion is smaller. As a result, the viscosity of the molten resin in the groove portion and in the vicinity of the peripheral edge of the mold cavity is increased rapidly, preventing a further volume of the molten resin from flowing into the groove portion. The sheet-like material in the vicinity of the peripheral edge is covered by the resinous material of diminished fluidity and protected against exposure to heat and/or pressure of the molten resin.

FIELD OF THE INVENTION

The present invention relates to an apparatus and method of injectionmolding for molding an article of synthetic resin simultaneously withintegrating a sheet-like material, such as a decorative sheet, onto asurface of the molded article in a cavity of an injection mold, and moreparticularly, to an apparatus and method of injection molding formolding an article of synthetic resign and simultaneously unifying asheet-like material on a surface of the molded article in a cavity of aninjection mold without causing damage to the sheet-like material duringa molding process.

BACKGROUND OF THE INVENTION

As disclosed in Japanese Patent Public Disclosure No. 2004-017508,Japanese Patent Publication No. S50-19132 and Japanese PatentPublication No. S43-27488, it has been proposed to perform a method ofinjection molding in order to unify a sheet-like material, such as adecorative or ornamental sheet, on a surface of a molded article duringa molding process and add new value or optional function to the moldedarticle due to the properties of the sheet-like material, such as color,pattern, quality of material and the like. A conventional method ofinjection molding of this kind exemplifies the following steps of:installing a decorative sheet in an injection mold, injecting a moltenresin to fill the mold cavity with the molten resin; and solidifying theresin in the cavity to form an injection molded body simultaneously withintegrating the decorative sheet onto a surface of the injection moldedbody.

In this method, the sheet-like material such as a decorative sheet ispre-shaped, as required, by an appropriate forming process such asvacuum forming to be adapted to the shape of the mold cavity whileinstalled in the mold or before installed in the mold. When installed inthe mold, the sheet-like material such as a decorative sheet covers thewhole or part of the mold cavity, and the area of the mold cavity thatis covered with the sheet-like material corresponds to the surface ofthe injection molded body onto which the sheet-like material should beintegrated. At this time, the remaining portion of the sheet-likematerial which protrudes outside the mold cavity is clamped between theparting surfaces or dividing surfaces or abutting surfaces of the firstand second mold sections, for example, a cavity mold and a core moldforming opposite sides of the mold cavity, so that the sheet-likematerial should not be displaced by injection pressure.

To take a pair of a cavity mold and a core mold as an example, thesheet-like material installed on the cavity mold extends continuouslyfrom a mold cavity on to a parting surface of the cavity mold, via theperipheral edge of the mold cavity of the cavity mold. Then the coremold is closed against the cavity mold and the sheet-like material isclamped between the parting surfaces of the core mold and the cavitymold while the sheet-like material extends in the mold cavity. Thesheet-like material extending in the mold cavity is defined by theperipheral edge of the mold cavity. When molten resign is injected intothe mold cavity from an injection gate of the core mold, the moltenresin flows along a surface of the sheet-like material to the peripheraledge of the mold cavity. Thereby, the mold cavity is filled with themolten resign and the sheet-like material defined by the peripheral edgeof the mold cavity.

The sheet-like material installed in the mold cavity is affected by thetemperature of the molten resin injected into the mold cavity and alsoaffected by the injection pressure of the molten resin produced to fillthe mold cavity up with the molten resin. The injected molted resintends to apply a large pressure to the sheet-like material, inparticular, in the vicinity of the peripheral edge of the mold cavity.Depending on conditions of injection molding, the sheet-like materialmay deform around the peripheral edge of the mold cavity. Especiallywhen the sheet-like material extends along an elongated peripheral edgeof the mold cavity, there is an increased risk of serious damage to thesheet-like material because of uneven dispersion of the molten resin. Inthe event that the sheet-like material is damaged, the molten resinleaks out of the mold cavity from the peripheral edge thereof andproduce a flash between the parting surfaces of the mold sections. Inaddition, the molten resin may penetrate through the sheet-like materialand damage the outer surface of an injection molded article to beproduced. When the sheet-like material is made of an olefin-basedthermoplastic elastomer (TPO) with soft texture or the like, theabove-mentioned disadvantages may cause serious damage to an injectionmolded article.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an apparatus ofinjection molding for molding an injection molded body and integrating asheet-like material onto a surface of the injection molded body withoutcausing damage to the sheet-like material.

Another object of the present invention is to provide an apparatus ofinjection molding for integrating a sheet-like material onto a surfaceof an injection molded body without causing damage to the sheet-likematerial.

Further object of the present invention is to provide an apparatus ofinjection molding for manufacturing an injection molded article integralwith a sheet-like material.

Another object of the present invention is to provide a method ofinjection molding for integrating a sheet-like material onto a surfaceof an injection molded article during fabrication of the injectionmolded article.

Further object of the present invention is to provide a method ofinjection molding for manufacturing an injection molded article ontowhich a sheet-like material is integrated during fabrication of theinjection molded article.

Another object of the present invention is to provide a method ofinjection molding for molding an injection molded article andintegrating a sheet-like material with the injection molded articleduring fabrication of the injection molded article, without causingdamage to the sheet-like material.

According to the first aspect of the present invention, there isprovided an apparatus of injection molding comprising: at least a pairof mold sections that can be closed and opened, wherein a sheet-likematerial can be disposed between said mold sections; a fixing device forfixing said sheet-like material at a set place interposed between saidmold sections; at least one mold cavity defined in said mold sectionswhen said mold sections are closed; and

an injection gate for injecting a molten resin into said mold cavity;characterized in that a groove or recess portion is formed outside theperipheral edge of said mold cavity, and said groove or recess portionis adapted to receive a molten resin that is injected into said moldcavity and flows into said groove or a recess portion through theperipheral edge of said mold cavity.

According the second aspect of the present invention, there is provideda method of injection molding wherein a molten resin injected into amold cavity and a sheet-like material supplied in mold sections areintegrated in said mold sections, and said molten resin integrated withsaid sheet-like material is molded by said mold sections, characterizedby the steps of: disposing said sheet-like material in said moldsections to expand from the interior of said mold cavity to the exteriorof said mold cavity continuously; fixing said sheet-like material tosaid mold sections; injecting said molten resin into said mold cavity tomold an injection molded body made from the molten resin filled in saidmold cavity and mold a protrusion made from the molten resin flowing outof the peripheral edge of said mold cavity, wherein said injectionmolded body is in close contact with said sheet-like material in theinterior of said mold cavity, said protrusion is in close contact withsaid sheet-like material in the exterior of said mold cavity, and saidprotrusion has a predetermined thickness; cooling said mold sections andincreasing a resin viscosity of said protrusion more rapidly than aresin viscosity of said injection molded body in said mold sections dueto the difference of the volume capacities between said protrusion andsaid injection molded body; and applying a predetermined pressure tosaid molted resin injected into said mold cavity when the resinviscosity of said protrusion has increased to a predetermined value, andintegrate said injection molded body and said protrusion with saidsheet-like material in said mold sections.

According to the third aspect of the present invention, there isprovided a method of injection molding for manufacturing an injectionmolded article with which a surface material is integrated,characterized by the steps of: disposing said sheet-like material insaid mold sections to expand from the interior of said mold cavity tothe exterior of said mold cavity continuously; fixing said sheet-likematerial to said mold sections; injecting said molten resin into saidmold cavity to mold an injection molded body made from the molten resinfilled in said mold cavity and mold a protrusion made from the moltenresin flowing out of the peripheral edge of said mold cavity, whereinsaid injection molded body is in close contact with said sheet-likematerial in the interior of said mold cavity, said protrusion is inclose contact with said sheet-like material in the exterior of said moldcavity, and said protrusion has a predetermined thickness; cooling saidmold sections and increasing a resin viscosity of said protrusion morerapidly than a resin viscosity of said injection molded body in saidmold sections due to the difference of the volume capacities betweensaid protrusion and said injection molded body; applying a predeterminedpressure to said molted resin injected into said mold cavity when theresin viscosity of said protrusion has increased to a predeterminedvalue, and integrate said injection molded body and said protrusion withsaid sheet-like material in said mold sections; and taking saidinjection molded body out of said mold sections, wherein said injectionmolded body has been integrated with said sheet-like material and moldedinto a predetermined shape, and cutting out said protrusion togetherwith the sheet-like material extending outside said mold cavity fromsaid injection molded body.

According to the present invention, one or more groove portions orrecess portions are formed on the whole or part of the peripheral edgesof the mold cavity in such a manner as to protrude from the mold cavityalong the surface of the sheet-like material in the direction in whichthe sheet-like material extends. Therefore, the molten material whichflows into the groove or recess portions from the mold cavity flowssmoothly along the sheet-like material at the peripheral edge of themold cavity. Thereby, it is possible to eliminate a risk where anexcessive pressure is applied to the sheet-like material lying at theperipheral edge of the mold cavity. Consequently, the temperature and/orpressure of the molten resin does not cause damage to the sheet-likematerial lying in the vicinity of the peripheral edge of the mold cavityduring molding process.

Due to the difference of the volume capacities between the protrusionand the injection molded body according to the present invention, aresin viscosity of said protrusion increases more rapidly than a resinviscosity of said injection molded body when cooling the mold sections.In other wards, the fluidity of the resinous material in the vicinity ofthe peripheral edge of the mold cavity is diminished more quickly thanthe fluidity of the resinous material in the mold cavity by cooling themold sections. Therefore, the sheet-like material lying in the vicinityof the peripheral edge of the cavity mold comes to be covered by theresinous material of diminished fluidity or increased viscosity so thatthe sheet-like material is protected against exposure to heat and/orpressure in the vicinity of the peripheral edge of said cavity mold.

In addition, the molten material flows smoothly in the vicinity of theedge portion of the mold cavity when the molten material is beinginjected, because the molten resin is received by the groove or recessportion at the peripheral edge of the mold cavity. Therefore, thesheet-like material can be prevented from being damaged by the heatand/or pressure of the molten resin accumulated in the vicinity of theperipheral edge of the mold cavity.

These and other objects and advantages of the present invention will bemore fully and readily understood by referring to the following detaileddescription of the present invention and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows exemplarily an apparatus of injection molding according tothe present invention, wherein FIG. 1A shows a state in which a mold isopened, and FIG. 1B shows a state in which the mold is closed.

FIG. 2A shows an enlarged sectional view of the area indicated by anarrow IIA in FIG. 1A, and FIG. 2B shows an enlarged sectional view ofthe area indicated by an arrow IIB in FIG. 1B.

FIG. 3 shows a perspective view of a meter cluster housing for vehicleswith which a TPO sheet is integrated.

FIG. 4 shows a vertical sectional view of an apparatus of injectionmolding for manufacturing the interior component for vehicles shown inFIG. 3, with a cavity mold and a core mold separated from each other toopen the cavity mold.

FIG. 5 shows a sectional view of a main part of the cavity mold and thecore mold in FIG. 4, which are brought into mating engagement to closethe mold cavity.

FIG. 6 shows as shown in FIG. 5.

FIG. 7 shows the vicinity of the peripheral edge of the mold cavitywherein a molten resin is injected into the mold cavity shown in FIG. 6.

FIG. 8 shows an enlarged sectional view of an edge portion of aninjection molded article which is taken out of the mold sections shownin FIG. 6.

FIG. 9 shows an enlarged sectional view of an edge portion of aninjection molded article after an unnecessary portion is trimmed offfrom the injection molded article shown in FIG. 8.

FIG. 10 shows an enlarged sectional view of the vicinity of a peripheraledge in a conventional mold cavity.

DETAILED DESCRIPTION OF THE INVENTION The First Embodiment

For a preferred embodiment of the present invention, one or more shallowgrooves are formed on a parting surface of a core mold. The groovesextend from an edge portion of a cavity in the core mold outwards of amold cavity so that an injected molten material flows into the groovessmoothly and is cooled quickly in the vicinity of an edge portion of themold cavity. When the injected molten material reached the edge portionof the cavity in the core mold, the molted material flows smoothlywithout staying on the edge portion of the cavity.

FIGS. 1 and 2 are drawings which show exemplarily an apparatus ofinjection molding according to the present invention, wherein the moldsections are open in FIG. 1A, while the mold sections are closed in FIG.1B. An apparatus of injection molding 1 has a cavity mold 2 and a coremold 3 in those figures, and when the core mold 3 are closed against thecavity mold 2 as shown in FIG. 1B, a mold cavity 4 is formed between thecavity mold 2 and the core mold 3.

A sheet-like material 5 such as a decorative sheet for a molded articleis formed of an olefin-based thermoplastic elastomer (TPO) or the likeso as to provide a surface of the molded article with soft texture. Thesheet-like material 5 may be pre-shaped by an apparatus of injectionmolding 1 using a suitable forming technique such as vacuum forming orthe like so as to match a cavity configuration of the cavity mold or maybe pre-shaped using any other vacuum forming system than the apparatus1. As shown in FIG. 1A, the sheet-like material 5, which has beenpre-shaped, is placed in the cavity mold 2. The pre-shaped sheet-likematerial 5 has a formed portion 5 a which is closely secured to a cavitysurface 2 a of the cavity mold 2 and a holding portion 5 b which extendsalong a parting surface 2 b of the cavity mold 2.

As shown in FIG. 2A, a groove portion 3 c is formed on an edge portion 3b of a cavity surface 3 a of the core mold 3. The groove portion 3 c ismade of a single annular groove which is open in a parting surface 3 dof the core mold 3. The groove portion 3 c extends from the edge portion3 b of the cavity surface 3 a outwards of the core mold 3 and existsalong the edge portion 3 b of the cavity surface 3 a in the core mold 3.

As shown in FIG. 1, the core mold 3 is closed against the cavity mold 2and then a molten resin 7 is injected into the mold cavity 4 from aninjection gate 6 in the core mold 3. The molten resin 7 injected intothe mold cavity 4 flows along an upper surface of the sheet-likematerial 5 mounted in the cavity mold 2 and reaches the edge portion 3 bof the cavity surface 3 a. As shown in FIG. 2B, the groove portion 3 cis made to open in the edge portion 3 b. Thereby, the molten resin 7flows along the upper surface of the sheet-like material 5 and smoothlyinto the groove portion 3 c without staying on the edge portion 3 b.When the mold cavity 4 and the groove portion 3 c are filled with themolten resin 7, the molten resin 7 is held under pressure in the moldsections 2 and 3 for a certain period of time. Simultaneously, the moldsections 2 and 3 are cooled by a cooling apparatus (not shown). Due tothe cooling process, the molten resin 7 is solidified to form a moldedbody (not shown) in the mold cavity 4, and the molded body is integratedonto the upper surface of the sheet-like material 5. During the coolingprocess, the molten resin 7 in the groove portion 3 c is hardened soonerthan the molten resin 7 in the mold cavity 4 becomes hardened, becausethe volume capacity of the groove portion 3 c is far smaller than thevolume capacity of the mold cavity 4. As the viscosity of the moltenresin 7 is increased in the groove portion 3 c, the fluidity of themolten resin 7 becomes diminished not only in the groove portion 3 c butalso in the vicinity of the edge portion 3 c of the cavity surface 8 aor a peripheral edge A of the mold cavity 4.

The diminished fluidity of the molten resin 7 prevents a further volumeof the molten resin 7 from flowing into the groove portion 3 c from themold cavity 4 and also prevents the migration of the molten resin 7 inthe vicinity of the peripheral edge A of the mold cavity 4. In thevicinity of the peripheral edge A of the mold cavity 4, the sheet-likematerial 5 comes to be covered by the molten resin 7 of increasedviscosity and protected against exposure to heat and/or pressure.Thereby, the molten resin 7 does not leak out between the partingsurface 3 d and the upper surface of the sheet-like material 5 to form aflash, even in the process that the molten resin 7 is pressurized at ahold pressure in the mold sections 2 and 3. In addition, the sheet-likematerial lying in the vicinity of the peripheral edge A of the moldcavity 4 is prevented from being deformed or damaged by the pressureand/or heat of the molten resin 7, because of the protective resincoating over the peripheral edge A of the mold cavity 4.

When the cooling process is completed, the mold sections 2 and 3 areseparated to open the mold cavity 4 and detach a semi-fabricated articleconsisting of the sheet-like material S and an injection molded body ofthe resin 7. The injection molded boy of the resin 7 is integrated ontothe upper surface of the sheet-like material 5. The semi-fabricatedarticle includes an extra part of the sheet-like material 5 whichextended between the parting surfaces 2 b and 3 d of the mold sections 2and 3 when molded. The semi-finished article also includes an extra partof the molded body in the form of an annular flange or the like, whichwas formed by the groove portion 3 c when molded. Therefore, the extraparts of the sheet-like material 5 and the molded body are cut to beremoved from the semi-fabricated article to obtain a finished product ofthe injection molded article.

The Second Embodiment

FIG. 3 illustrates a perspective view an automotive interior part, thatis, a meter cluster housing 8. As a decorative sheet, a TPO sheet 9having a soft texture is integrated onto a surface of the housing 8.Hereinafter, the present invention will be described further by takingas an example a manufacture of the meter cluster housing 8 with whichthe TPO sheet 9 is integrated. The flange-like protrusion that is madefrom the molten resin 7 filled in the groove portion 3 c in FIG. 2B isformed along a front edge portion 8 A of the meter cluster housing 8 andis positioned on a back side of the TPO sheet 9 extending toward theoutside of the front edge portion 8A.

In FIG. 4, the TPO sheet 9 is heated by a heating device (not shown) soas to be softened and fixed to a parting surface of a cavity mold 11 ofan apparatus of injection molding 10 by means of dampers 12, 12. In thisexample, the cavity mold 11 is a stationary mold held by a base member13 and a plurality of suction ports 14, 15, 16 are formed in the cavitymold 11 and the base member 13. The TPO sheet 9 supplied on the cavitymold 11 is sucked by virtue of vacuum created in air suction ports 14,15, 16 so as to be closely secured to a mold surface of the cavity mold11 by means of vacuum forming. Thereby, the TPO sheet 9 is pre-shaped toconform with the mold surface of the cavity mold 11, which correspondsto a surface configuration of a meter cluster housing 8 to be molded.

A core mold 17 disposed above the cavity mold 11 is held by an upperflame 18 as a movable mold of the apparatus of injection molding 10. Inthe core mold 17, a pair of injection gates 20 a, 20 b and a pair ofejector rods or ejector pins 21, 22 are installed in order to remove amolded article from the mold sections 11, 17. When the pre-shaping ofthe TPO sheet 9 is completed, the core mold 17 is lowered together withthe upper frame 18 and the core mold 17 is closed against the cavitymold 11 to define a mold cavities 19 a, 19 b between the core mold 17and the cavity mold 11 as illustrated in FIG. 5. Then, a molten resin isinjected into the mold cavity 19 a from a injection gate 20 a to form avisor portion 8 a of the meter cluster housing 8 and simultaneously, amolten resin is injected into the mold cavity 19 b from an injectiongate 20 b to form a shelf portions 8 b, 8 b of the meter cluster housing8. Since the mold cavities 19 a, 19 b communicate with each other viaone or more communicating paths (not shown) formed between the moldcavities 19 a, 19 b, the molted resin flowed into the communicatingpaths forms a mounting portion 8 c on which various instruments such asmeters are mounted. In those figures, reference numeral 23 denotes aseal member for sealing a gap between the TPO sheet 9 and the partingsurface of the cavity mold 11 in cooperation with the dampers 12.Reference numeral 24 denotes a detachable piece which makes up part ofthe cavity mold 11 to be replaced when it gets worn.

As illustrated in FIG. 6, a groove portion 17 b is formed on the partingsurface of the core mold 17. The groove portion 17 b is in the form ofan elongated step extending along the end portion 17 a of the cavitysurface in the core mold 17. The end portion 17 a corresponds to aperipheral edge A of the mold cavity 19 a as shown in FIG. 6. The grooveportion 17 b is made up of a single groove that extends to curve alongan outer side of the peripheral edge A of the mold cavity 19 a as toform a thin protrusion 25 a of a molded body 25 as illustrated in FIG.8. The thin protrusion 25 a is in the form of a flap that is made from amolten resin injected into the mold cavity 19 a and integrated onto anupper surface of the TPO sheet 9 as shown in FIGS. 7 and 8. The thinprotrusion 25 a is made of resin flowing into the groove portion 17 bfrom the mold cavity 19 a as illustrated in FIG. 7.

FIG. 10 shows, on the contrary, a vertical section of the mold sections17, 18 that has no groove 17 b in the peripheral edge A of the moldcavity 19 a. Comparing FIG. 10 to FIG. 7, it is apparent where the thinprotrusion 25 a is formed.

Now, the molted resin 25 is injected from the injection gates 20 a, 20 binto the mold cavities 19 a, 19 b after the core mold 17 is closedagainst the cavity mold 18. The molted resin injected into the moldcavity 19 a flows along the upper surface of the TPO sheet 9 towards theperipheral edge A of the mold cavity 19 a while filling the mold cavity19 a. As the molten resin reached the peripheral edge A of the moldcavity 19 a, the molten resin passes smoothly the peripheral edge A ofthe mold cavity 19 a and flows into the groove portion 17 b withoutstaying in the vicinity of the peripheral edge A of the mold cavity 19 aor the end portion 17 a of the cavity surface of the core mold 17. Whenthe mold cavities 19 a, 19 b and the groove portion 17 b as well as thecommunicating paths between the mold cavities 19 a, 19 b are filled withthe molten resin, the injected molten resin is held under pressure inthe mold sections 17, 18 for a certain period of time and is cooled downby a cooling device (not shown).

When cooling down the molten metal in the mold sections 17, 18, thetemperature of the molten resin filled in the groove portion 17 bdecreases more quickly than the temperature of the molten resin withinthe mold cavities 19 a, 19 b because the volume capacity of the grooveportion 17 c is smaller than the volume capacity of the mold cavities 19a, 19 b in the mold sections 17, 18. As a result that the viscosity ofthe molten resin is increased in the groove portion 17 c, the fluidityof the molten resin becomes diminished not only in the groove portion 17c but also in the vicinity of the peripheral edge A of the mold cavity19 a. The diminished fluidity of the molten resin prevents a furthervolume of the molten resin from flowing into the groove portion 17 bfrom the mold cavity 19 a and also prevents the migration of the moltenresin in the vicinity of the peripheral edge A of the mold cavity 19 a.In the vicinity of the peripheral edge A of the mold cavity 19 a,thereby, the TPO sheet 9 comes to be covered by the molten resin ofincreased viscosity and protected against exposure to heat and/orpressure of the molten resin in the mold cavity 19 a. As a result, theTPO sheet 9 lying in the vicinity of the peripheral edge A of the moldcavity 19 a is prevented from being deformed or damaged by the pressureand/or heat of the molten resin. Therefore, the molten resin injectedinto the mold cavities 19 a, 19 b does not leak out between the partingsurface of the core mold 17 and the upper surface of the TOP sheet 9 toform a flash, even in the event that a molding pressure is appliedfurther to the molten resin within the mold cavities 19 a, 19 b in thesubsequent pressure holding step.

When the cooling down of the molten resin in the mold sections 17, 18 iscompleted, a molded body 25 is molded in the mold cavities 19 a, 19 band the communicating paths (not shown) and integrated onto the uppersurface of the TPO sheet 9 as illustrated in FIGS. 7 and 8.Simultaneously, the thin protrusion 25 a of resin is molded in thegroove portion 17 b and integrated onto the upper surface of the TPOsheet 9. The thin protrusion 25 a extends from the edge of the moldedbody 25 as shown in FIG. 8. Then, the core mold 17 is lifted from thecavity mold IS to open the mold cavities 19 a, 19 b and the molded body25 is removed from the mold sections 17, 18 together with the TPO sheet9 by means of the ejector rods 21, 22. The molded article took out ofthe mold sections 17, 18 is a semi-fabricated article of a meter clusterhousing 8, because it includes an extra part of the TPO sheet 9extending from the molded body 25 and the thin protrusion 25 aintegrated onto the extra part of the TPO sheet 9 as shown in FIG. 8.Therefore, the semi-fabricated article is processed for a trimmingoperation by which the extra part of the TPO sheet 9 and the thinprotrusion 25 a is trimmed off, as shown in FIG. 9, to obtain a finishedproduct of the meter cluster housing 8.

1. An apparatus for injection molding comprising: at least a pair of mold sections that can be closed and opened, wherein a sheet-like material can be disposed between said mold sections; a fixing device for fixing said sheet-like material at a set place interposed between said mold sections; at least one mold cavity defined in said mold sections when said mold sections are closed; an injection gate for injecting a molten resin into said mold cavity; and a groove or recess portion outside the peripheral edge of said mold cavity, said groove or recess portion receiving a molten resin that is injected into said mold cavity and flows into said groove or a recess portion through a peripheral edge of said mold cavity.
 2. The apparatus for injection molding as set forth in claim 1, wherein said groove or recess portion extends along at least a part of the peripheral edge of said mold cavity.
 3. The apparatus for injection molding as set forth in claim 1, wherein said groove or recess portion is in the form of an elongated step, on a parting surface of one of said mold sections and extends along the peripheral edge of said mold cavity.
 4. The apparatus for injection molding as set forth in claim 1, wherein said mold sections comprise a cavity mold and a core mold, said cavity mold is fixed and said core mold reciprocates relative to said cavity mold, and said mold cavity is defined by a cavity surface on the parting surface of said cavity mold and another cavity surface on the parting surface of said core mold, when said core mold is closed against said cavity mold.
 5. The apparatus for injection molding as set forth in claim 4, wherein said apparatus comprises one or more clampers for fixing said sheet-like material to the parting surface of said cavity mold.
 6. The apparatus for injection molding as set forth in claim 5, wherein said groove or recess portion is formed on the parting surface of said core mold, said groove or recess portion extends outside a peripheral edge of said cavity surface, and said groove or recess portion receives a molten resin injected into said mold cavity, said molten resin flows into said groove or recess portion through the peripheral edge of said cavity mold and disperses along a surface of said sheet-like material within said groove or recess portion.
 7. A The apparatus for injection molding as set forth in claim 4, wherein said core mold comprises one or more air suction holes for vacuum molding, and said air suction holes have openings in the cavity surface and/or parting surface of said cavity mold.
 8. The apparatus for injection molding as set forth in claim 7, wherein said apparatus comprises one or more dampers for fixing said sheet-like material to said parting surface of said cavity mold, and sealing means disposed in said parting surface of said cavity mold so as to seal said sheet-like material against said parting surface in cooperation with said clampers.
 9. The apparatus for injection molding as set forth in claim 4, wherein said core mold comprises one or more injection gates for injecting a molten resin into said mold cavity of the mold sections.
 10. A method of injection molding wherein a molten resin injected into a mold cavity and a sheet-like material supplied in mold sections are integrated in said mold sections, and said molten resin integrated with said sheet-like material is molded by said mold sections, the method comprising: disposing said sheet-like material in said mold sections to expand from the interior of said mold cavity to the exterior of said mold cavity continuously; fixing said sheet-like material to said mold sections; injecting said molten resin into said mold cavity to mold an injection molded body made from the molten resin filled in said mold cavity and mold a protrusion made from the molten resin flowing out of the peripheral edge of said mold cavity, wherein said injection molded body is in close contact with said sheet-like material in the interior of said mold cavity, said protrusion is in close contact with said sheet-like material in the exterior of said mold cavity, and said protrusion has a predetermined thickness; cooling said mold sections and increasing a resin viscosity of said protrusion more rapidly than a resin viscosity of said injection molded body in said mold sections due to the difference of the volume capacities between said protrusion and said injection molded body; and applying a predetermined pressure to said molted resin injected into said mold cavity when the resin viscosity of said protrusion has increased to a predetermined value, and integrate said injection molded body and said protrusion with said sheet-like material in said mold sections.
 11. The method of injection molding as set forth in claim 10, including forming said resinous protrusion from the molten resin that has flowed into a groove or recess portion from said mold cavity, wherein said groove or recess portion is outside the peripheral edge of said mold cavity and extends along a surface of said sheet-like material in said mold sections.
 12. The method of injection molding as set forth in claim 11, wherein said molten resin moves smoothly in the vicinity of the peripheral edge of said mold cavity and flows into said groove or recess portion from said mold cavity.
 13. The method of injection molding as set forth in claim 11, wherein the fluidity of the resinous material of said protrusion is diminished by cooling said mold sections, and the diminished fluidity of the resinous material of said protrusion prevents a further volume of the molten resin from flowing into said groove or recess portion from the mold cavity.
 14. The method of injection molding as set forth in claim 10, wherein said sheet-like material is a decorative sheet made of an olefin-based thermoplastic elastomer (TPO).
 15. The method of injection molding as set forth in claim 10, wherein the fluidity of the resinous material in the vicinity of the peripheral edge of said mold cavity is diminished by cooling said mold sections, and the sheet-like material lying in the vicinity of the peripheral edge of said cavity mold comes to be covered by the resinous material of diminished fluidity or increased viscosity so that said sheet-like material is protected against exposure to heat and/or pressure in the vicinity of the peripheral edge of said cavity mold.
 16. The method of injection molding as set forth in claim 11, wherein said mold cavity is defined between a cavity surface of said cavity mold and a cavity surface of said core mold, and said core mold reciprocates relative to said cavity mold to define said cavity mold when closed against said cavity mold.
 17. The method of injection molding as set forth in claim 16, including supplying said sheet-like material to the parting surface of said cavity mold when said cavity mold and said core mold are separated, and then fixing said sheet-like material to the parting surface of said cavity mold by one or more clampers so said sheet-like material extends across the parting surface and the cavity surface of said cavity mold.
 18. The method of injection molding as set forth in claim 17, including fixing said sheet-like material to the parting surface of said cavity mold to seal the cavity surface of said cavity mold from the atmosphere, and then pre-shaping said sheet-like material by the cavity surface of said cavity mold by vacuum molding.
 19. The method of injection molding as set forth in claim 17 comprising: closing said core mold against said cavity mold and disposing said sheet-like material within said mold cavity, and, simultaneously, defining said groove or recess portion between the parting surface of said core mold and said sheet-like material extending outside said mold cavity, wherein said groove or recess portion has an opening in the peripheral edge of said mold cavity; injecting a molten resin into said mold cavity defined between the cavity surface of said core mold and said sheet-like material disposed within said mold cavity and forming an injection molded body, wherein said injection molded body is in close contact with said sheet-like material in said mold cavity, and filling said groove or recess portion wit said molten resin to form a resinous protrusion having a predetermined thickness, wherein said resinous protrusion is in close contact with said sheet-like material outside said mold cavity; cooling said core mold and said cavity mold and increasing a resin viscosity of said protrusion more rapidly than a resin viscosity of said injection molded body in said mold sections due to the difference of the volume capacities between said protrusion and said injection molded body; and applying a predetermined pressure to said molted resin injected into said mold cavity when the resin viscosity of said protrusion has increased to a predetermined value, and integrate said injection molded body and said protrusion with said sheet-like material in said mold sections.
 20. A method of injection molding for manufacturing an injection molded article with which a surface material is integrated, comprising: disposing said sheet-like material in said mold sections to expand from the interior of said mold cavity to the exterior of said mold cavity continuously; fixing said sheet-like material to said mold sections; injecting said molten resin into said mold cavity to mold an injection molded body made from the molten resin filled in said mold cavity and mold a protrusion made from the molten resin flowing out of the peripheral edge of said mold cavity, wherein said injection molded body is in close contact with said sheet-like material in the interior of said mold cavity, said protrusion is in close contact with said sheet-like material in the exterior of said mold cavity, and said protrusion has a predetermined thickness; cooling said mold sections and increasing a resin viscosity of said protrusion more rapidly than a resin viscosity of said injection molded body in said mold sections due to the difference of the volume capacities between said protrusion and said injection molded body; applying a predetermined pressure to said molted resin injected into said mold cavity when the resin viscosity of said protrusion has increased to a predetermined value, and integrate said injection molded body and said protrusion with said sheet-like material in said mold sections; and taking said injection molded body out of said mold sections, wherein said injection molded body has been integrated with said sheet-like material and molded into a predetermined shape, and cutting out said protrusion together with the sheet-like material extending outside said mold cavity from said injection molded body.
 21. The method of injection molding as set forth in claim 20, wherein said resinous protrusion is formed from the molten resin that has flowed into a groove or recess portion from said mold cavity, and said groove or recess portion is formed outside the peripheral edge of said mold cavity to extend along a surface of said sheet-like material in said mold sections,
 22. The method of injection molding as set forth in claim 21, wherein said molten resin moves smoothly in the vicinity of the peripheral edge of said mold cavity and flows into said groove or recess portion from said mold cavity.
 23. The method of injection molding as set forth in claim 21, wherein the fluidity of the resinous material of said protrusion is diminished by cooling said mold sections, and the diminished fluidity of the resinous material of said protrusion prevents a further volume of the molten resin from flowing into said groove or recess portion from the mold cavity.
 24. The method of injection molding as set forth in claim 20, wherein said sheet-like material is a decorative sheet made of an olefin-based thermoplastic elastomer (TPO).
 25. The method of injection molding as set forth in claim 20, wherein the fluidity of the resinous material in the vicinity of the peripheral edge of said mold cavity is diminished by cooling said mold sections, and the sheet-like material lying in the vicinity of the peripheral edge of said cavity mold comes to be covered by the resinous material of diminished fluidity or increased viscosity so that said sheet-like material is protected against exposure to heat and/or pressure in the vicinity of the peripheral edge of said cavity mold.
 26. A The method of injection molding as set forth in claim 21, wherein said mold cavity is defined between a cavity surface of said cavity mold and a cavity surface of said core mold, and said core mold reciprocates relative to said cavity mold to define said cavity mold when closed against said cavity mold.
 27. The method of injection molding as set forth in claim 26, including supplying said sheet-like material to the parting surface of said cavity mold when said cavity mold and said core mold are separated, and then fixing said sheet-like material to the parting surface of said cavity mold by one or more clampers so the sheet-like material extends across the parting surface and the cavity surface of said cavity mold.
 28. The method of injection molding as set forth in claim 27, including fixing said sheet-like material to the parting surface of said cavity mold to seal the cavity surface of said cavity mold from the atmosphere, and then pre-shaping said sheet-like material by the cavity surface of said cavity mold by vacuum molding.
 29. The method of injection molding as set forth in claim 27: closing said core mold against said cavity mold and disposing said sheet-like material within said mold cavity, and, simultaneously, defining said groove or recess portion between the parting surface of said core mold and said sheet-like material extending outside said mold cavity, wherein said groove or recess portion has an opening in the peripheral edge of said mold cavity; injecting a molten resin into said mold cavity defined between the cavity surface of said core mold and said sheet-like material disposed within said mold cavity and forming an injection molded body, wherein said injection molded body is in close contact with said sheet-like material in said mold cavity, and filling said groove or recess portion with said molten resin to form a resinous protrusion having a predetermined thickness, wherein said resinous protrusion is in close contact with said sheet-like material outside said mold cavity; cooling said core mold and said cavity mold and increasing a resin viscosity of said protrusion more rapidly than a resin viscosity of said injection molded body in said mold sections due to the difference of the volume capacities between said protrusion and said injection molded body; and applying a predetermined pressure to said molted resin injected into said mold cavity when the resin viscosity of said protrusion has increased to a predetermined value, and integrate said injection molded body and said protrusion with said sheet-like material in said mold sections; and taking said injection molded body out of said mold sections, wherein said injection molded body has been integrated with said sheet-like material and molded into a predetermined shape, and cutting out said protrusion together with the sheet-like material extending outside said mold cavity from said injection molded body.
 30. The method of injection molding as set forth in claim 29, wherein said injection molded article is an interior component for vehicles.
 31. The apparatus for injection molding as set forth in claim 2, wherein said groove or recess portion is in the form of an elongated step, on a parting surface of one of said mold sections and extends along the peripheral edge of said mold cavity.
 32. The method of injection molding as set forth in claim 14, wherein the fluidity of the resinous material in the vicinity of the peripheral edge of said mold cavity is diminished by cooling said mold sections, and the sheet-like material lying in the vicinity of the peripheral edge of said cavity mold comes to be covered by the resinous material of diminished fluidity or increased viscosity so that said sheet-like material is protected against exposure to heat and/or pressure in the vicinity of the peripheral edge of said cavity mold.
 33. The method of injection molding as set forth in claim 18, comprising: closing said core mold against said cavity mold and disposing said sheet-like material within said mold cavity, and, simultaneously, defining said groove or recess portion between the parting surface of said core mold and said sheet-like material extending outside said mold cavity, wherein said groove or recess portion has an opening in the peripheral edge of said mold cavity; injecting a molten resin into said mold cavity defined between the cavity surface of said core mold and said sheet-like material disposed within said mold cavity and forming an injection molded body, wherein said injection molded body is in close contact with said sheet-like material in said mold cavity, and filling said groove or recess portion with said molten resin to form a resinous protrusion having a predetermined thickness, wherein said resinous protrusion is in close contact with said sheet-like material outside said mold cavity; cooling said core mold and said cavity mold and increasing a resin viscosity of said protrusion more rapidly than a resin viscosity of said injection molded body in said mold sections due to the difference of the volume capacities between said protrusion and said injection molded body; and applying a predetermined pressure to said molted resin injected into said mold cavity when the resin viscosity of said protrusion has increased to a predetermined value, and integrate said injection molded body and said protrusion with said sheet-like material in said mold sections.
 34. The method of injection molding as set forth in claim 23, wherein the fluidity of the resinous material in the vicinity of the peripheral edge of said mold cavity is diminished by cooling said mold sections, and the sheet-like material lying in the vicinity of the peripheral edge of said cavity mold comes to be covered by the resinous material of diminished fluidity or increased viscosity so that said sheet-like material is protected against exposure to heat and/or pressure in the vicinity of the peripheral edge of said cavity mold.
 35. The method of injection molding as set forth in claim 24, wherein the fluidity of the resinous material in the vicinity of the peripheral edge of said mold cavity is diminished by cooling said mold sections, and the sheet-like material lying in the vicinity of the peripheral edge of said cavity mold comes to be covered by the resinous material of diminished fluidity or increased viscosity so that said sheet-like material is protected against exposure to heat and/or pressure in the vicinity of the peripheral edge of said cavity mold.
 36. The method of injection molding as set forth in claim 28, closing said core mold against said cavity mold and disposing said sheet-like material within said mold cavity, and, simultaneously, defining said groove or recess portion between the parting surface of said core mold and said sheet-like material extending outside said mold cavity, wherein said groove or recess portion has an opening in the peripheral edge of said mold cavity; injecting a molten resin into said mold cavity defined between the cavity surface of said core mold and said sheet-like material disposed within said mold cavity and forming an injection molded body, wherein said injection molded body is in close contact with said sheet-like material in said mold cavity, and filling said groove or recess portion with said molten resin to form a resinous protrusion having a predetermined thickness, wherein said resinous protrusion is in close contact with said sheet-like material outside said mold cavity; cooling said core mold and said cavity mold and increasing a resin viscosity of said protrusion more rapidly than a resin viscosity of said injection molded body in said mold sections due to the difference of the volume capacities between said protrusion and said injection molded body; and applying a predetermined pressure to said molted resin injected into said mold cavity when the resin viscosity of said protrusion has increased to a predetermined value, and integrate said injection molded body and said protrusion with said sheet-like material in said mold sections; and taking said injection molded body out of said mold sections, wherein said injection molded body has been integrated with said sheet-like material and molded into a predetermined shape, and cutting out said protrusion together with the sheet-like material extending outside said mold cavity from said injection molded body. 